A statement from the municipal health authorities said 120 patients who had received treatment at the clinic were traced and screened for the disease, and 95 of them are suspected to have been infected with the disease, which the World Health Organization says can lead to cirrhosis of the liver and liver cancer.

Local authorities launched an investigation after being tipped off on January 28 that patients who had received varicose vein treatment at a privately-run clinic were suspected to have been infected with hepatitis C.

Preliminary investigation has not ruled out the possibility of improper medical behavior of the clinic as the cause of the outbreak. Further investigation is underway. Hepatitis C is viral and is mainly transmitted through contact with contaminated blood, although it can also spread through sexual contact and from mother to child during delivery.

The doctor, surnamed Xue, working as a surgeon at the clinic in the city of Donggang, was detained by local police on February 2 and is being investigated, according to sources with the city’s health bureau.

The clinic has been ordered to close. A further investigation is underway, the sources said.

Although illegal blood donation practices were stopped by the Chinese government in the late 1990s, methods of collecting and storing blood need to be urgently improved to stop the virus spreading further, say the team.